Just a guess, here from my own experience below decks on the USS Constellation (sister ship to Old Ironsides, iirc). While topside, there was plenty of room for a six-foot tall guy, below decks I had to walk hunched over to avoid hitting my head on the beams. Spend months or years of strenuous activity in 'short' quarters, and that'd affect your back.
I'd imagine there were few green recruits aboard the state-of-the-art flagship, hence the occupational injuries, and it is unlikely sleeping in hammocks would provide much relief.
Those who worked aloft would tend to be younger and their bodies would be carried away by currents more than those below decks, so the preservation bias would be for the bodies of the guncrews.
The Navy was manned quite differently in Henry VIII’s day. The only true seamen where those required to handle sails and rigging - the men in the tops, and weather decks. All the rest were landsmen, soldiers really, and they manned the guns and all of the other weapons as well as providing the general labor. The seamen came from the merchant fleets and went back to them when the campaigning season was over.